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By M Johnson, M Horrigan

The scope of this report is to examine the aforementioned hypothesis by performing a detailed analytical comparison of a P&H electric rope shovel to an O&K diesel powered hydraulic excavator. In order to complement the integrity of the concluding results, two different size categories will be analysed in order to demonstrate that the findings can be extrapolated and applied to all the machinesÆ size classes. These two size classes are categorised by their bucket sizes and they are in the range of 43 - 58 cubic metres and 23 - 26 cubic metres. It should be noted that electric powered hydraulic excavators will not be considered in this report. In order to compare the electric and hydraulic types, the machine variants that will be analysed are commercial cost-effectiveness and operational flexibility. Although operational flexibility can be an ambiguous characteristic, a clear and thorough definition describing its exact meaning has been included. In order to simplify this study, all the data collected for this comparison have been for overburden removal, eliminating the variation that occurs with the movements of the shovel when selectively mining in the ore deposit. Thus, it ensures that all the data that is compared stems from a common origin for all the shovels. In other words the information will be compared when digging in the same material, loading into the same sized haul trucks, and when possible, with the same operators. Theoretical data received form the respective manufacturers, and actual data obtained from Mount Whaleback, was used for this comparison. This leads to the final comparison, where the operational flexibility and the cost-effectiveness are evaluated, with respect to their individual importance, ultimately influencing the final recommendation.

Jan 1, 2002

Copper Extraction from Scrap Cables by Biotechnological Means

Sep 13, 2010

Crushing Plant Process Optimisation Design of processes in order to find the most efficient solution to a specific task is a difficult problem. Often the number of solutions are large and the optimal solution is therefore difficult to identify. Crushing plant process design is no exception from this statement. In order to find the best solution issues like equipment selection and process configuration must be mastered. The solution must both be technically feasible and preferably have a low operating cost. Since crushing plant design is a complex task with a large solution space it is basically impossible to master without a specialised tool. For a long time simulation softwares have been used to assist in the design process. These tools only give answers for how a user defined plant will operate. There are no tools with capabilities to consider different design options in order to determine what the most efficient solution looks like. In this paper a method for crushing plant design optimisation is presented. The novel method utilises a combined optimisation routine and expert system in order to find the most cost efficient solution to a given process task. The user will only need to define the feed material properties, the process capacity, and the end product requirements. The developed system will find the solution lowest production cost per ton.

Sep 13, 2010

The need for legislative reform of health and safety legislation has been recognised in New Zealand for about a decade. Previous legislation did not cover all work places, many areas were excluded from coverage, and there were at least 14 different acts and dozens of sets of regulations dealing with various aspects of health and safety.

Jan 1, 1993

By T F. Guerin

Explorationn and mining have shown to cause significant impacts to the terrestrial and marine environment. Current mining and exploration techniques are outlined in the light of their potential to impact upon the environment, ie negligibly, negatively or positively. A profile of five Australian-based gold producers is presented. The development of protocols to specifically deal with the highly regulated and ever changing, mining and environmental legislation. demonstrates mining companies can successfully opcrationalise the concept of sustainable development.

Jan 1, 1992

By L Reynolds

Oceana Gold (New Zealand) Limited (OceanaGold) has commenced mining operations at the Globe-Progress mine in the Reefton Goldfield, an area that historically produced 2.1 million ounces of gold from underground quartz lode deposits. During the construction phase of the operation, advanced exploration programmes targeting near-mine prospects commenced. The focus of this ongoing exploration is the discovery of near surface, refractory gold deposits that are amenable to open-pit mining methods and treatment through the Globe-Progress process plant.   One such discovery is the Supreme deposit, located along strike approximately 3 kilometres to the south of the Globe-Progress mine. The Supreme area was tested extensively with diamond drilling in 2006, defining a deposit with similar mineralisation styles and grade to the Globe-Progress deposit. The mineralisation comprises a central core of gold-bearing quartz veins, locally containing visible gold, surrounded by a more extensive halo of refractory, disseminated gold associated with an arsenopyrite-pyrite sulphide mineral assemblage. Three subparallel mineralised structures host the mineralisation. These structures are highly oblique to the country rock orientations, extending approximately 250 metres along a northeast-southwest strike and at least 220 metres down-dip, with an average thickness of 12 metres and moderate dip to the southeast. Records of historical workings indicate that mineralisation extends further down-dip and remains open at depth. 5175 ounces of gold were mined historically at the Supreme deposit. OceanaGold have defined an Inferred Resource for the Supreme deposit of 0.84 million tonnes at 1.46 grams per tonne for a total of 40 000 ounces (at a 0.8 grams per tonne cut-off). Higher-grade zones of mineralisation exist within the deposit and further drilling is planned to test the extent, continuity and geological controls of the mineralised structures.

Jan 1, 2007

By S Taylor, B Lumsden, G Long

Statistical metallurgical plant trials are becoming more widespread, as a valuable tool for increasing plant profitability. Generally, a single parameter like metal recovery varies under the trial condition while all other variables such as average metal feed grade or average metal concentrate grade are equal for the two test conditions during the period of the test. Metal recovery is usually the measured variable because concentrate grade is fixed by smelter terms, and plants operate to maximise recovery at the required concentrate grade. However, in all flotation plants there is a relationship between concentrate grade and metal recovery, and under the same conditions increasing one results in a decrease in the other. At MMGÆs Rosebery Mine the zinc concentrate produced is generally above smelter specifications, so zinc concentrate grade can vary during a test. During trialling of magnetic conditioning in the Rosebery zinc circuit, the difference in both zinc recovery and zinc concentrate grade were analysed. The analysis of changes in zinc grade and recovery during the trial raised some interesting questions about the relationship between concentrate grade and recovery. A paired statistical method was developed and tested to combine in each pair the change in concentrate grade and recovery in a single result that could be analysed by a paired t test. This method was found to be very sensitive to combined, varying changes in concentrate grade and/or metal recovery. It was also evaluated on plant test results from another flotation plant to verify its applicability in other plants. CITATION:Long, G, Taylor, S and Lumsden, B, 2012. Statistical plant trials - Efficiently combining concentrate grade and metal recovery results, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 355-362 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Sapporo-Iwanai district is located at the intersection of the northeast Japan arc and Kuril arc, associated with the subduction zone. This area is characterized by Miocene submarine volcanism followed by Plio-Pleistocene subaerial volcanism.   Koryu, a small epithermal Au-Ag deposit, occurred in Pleistocene (1.4 - 0.85 Ma) within Miocene sedimentary rocks near a subaerial andesitic volcano, while Toyoha, a large epithermal Pb-Zn-Ag (-Au) deposit, also occurred near a subaerial andesitic volcano. Although most of the base metal deposits formed in middle-late Miocene, Toyoha formed in Plio-Pleistocene (2.93 - 1.60 Ma) within Miocene volcanic and sedimentary rocks. This epithermal mineralization was partly overprinted by xenothermal Cu-Sn-In(-Au) mineralization (2.68 - 0.49 Ma).   Hydrothermal alteration differs vastly between Koryu and Toyoha: host rocks at Koryu were not intensively altered, although wall rocks adjacent to veins were silicified, while those at Toyoha show intensive and extensive neutral-pH alterations. Geological and chronological studies show that middle~late Miocene (12.5 - 8.4 Ma) alteration was pervasive and overprinted by Plio-Pleistocene (2.93 - 0.49 Ma) alteration. The base metal veins in the middle-late Miocene were not well developed, but were large in number with great depth.   These studies show that the hydrothermal activity at Koryu is rather small and short-lived, while that at Toyoha is large, long-lived and characterized by overprinting of different hydrothermal systems. The subaerial magmatic activities yielded not only the andesite lavas, but also generated hydrothermal solutions for the formation of both Koryu and Toyoha. The metals were possibly derived from such magma. At Toyoha, the hydrothermal solutions could also remobilize metals from old ores.   The size, life span of magmatic-hydrothermal system, and overprinting on the old mineralizing systems could constrain the type of metal deposits (precious and polymetallic deposits) nearby subaerial andesitic volcanoes in Plio-Pleistocene.

Jan 1, 2005

By H Kurth

Geoscan is used for multi-elemental analysis of conveyed bulk materials in real time. It has been used for coal analysis since the 1990s, in the cement industry, and since 2003 for measuring mineral ore quality. Geoscan-M has proven performance and demonstrated paybacks of weeks or months, in iron ore, manganese, copper, zinc-lead and phosphate industries. Geoscan-M measures continuously through the full bed depth and is unaffected by belt speed, particle size, layering and dust levels. Increments of two minutes (typically one to five minutes) are accurately measured and provide the plant operators with tonnage weighted results of each element within seconds.A Geoscan installed after crushing is able to measure quality shortly after mining. The analysis results can be used to divert the increments based on composition, such as diverting waste for disposal and diverting marginal material to a stockpile for processing at a later date. The bulk sorting process allows different qualities to be placed into relevant stockpiles for subsequent blending. Material meeting product DSO (Direct Shipping Ore) quality can bypass a beneficiation circuit to prevent unnecessary treatment costs. An analyser in a blending application enables proportioning of different quality feed materials from multiple stockpiles to achieve a desired compositional consistency for process feed. The parameter used for decisions may be; a) primary metal content, e.g. Cu, Fe, P, etc. b) deleterious component content, e.g. Mg as an indicator of talc content, c) process parameter content, or a combination of these. Process parameter content may be the elemental ratio between critical components, e.g. Cu:S ratio, Fe:Si ratio, basicity, Lime Saturation Factor, etc. or the content of an “indicator” element, e.g. Si as an indicator of material hardness or grindability.Measurement of the composition in real time enables prompt feedback to the mining operators and also feed forward to the process operators. Compositional variability can be critical in the process and advance warning enables appropriate reactions prior to processing. This may include modifying the feed rate, changing the feed blend (through additives), or modifying reagent dosing in anticipation of a change in feed quality. Benefits include, but are not limited to; reducing waste processing, improved feed grade stability, reducing energy, water and grinding media consumption, producing less tailings, increasing process efficiency, higher metal recovery, better plant utilisation, reducing plant downtime, better utilising mined material, all achieved using the same process plant throughput capacity.CITATION:Kurth, H, 2015. Optimising plant feed quality and process performance using Geoscan elemental analysis, in Proceedings MetPlant 2015, pp 373–380 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By D M. Marques, J F. C L Costa

The estimation of process plant head grade is not trivial and is a source of constant dispute within the mining industry. Grade estimates informed by the short term mine planning are frequently not reproduced by sampling the continuous flow of ore at the plant. Head grades are normally obtained by periodically sampling the continuous flow during a day or shift, and taking the average of the multiple increments collected. The standard error of this mean grade depends on the ore variability and the frequency (number) of aliquots extracted. The more increments are taken the higher is the precision on the calculated mean. Variographic experiments are normally used to map grade variability along a certain period of time and the extension variance is derived from this variogram. This experiment is time consuming, expensive and cumbersome. Mining industry personnel rarely apply this approach. Additionally, a temporal variogram can vary from day to day as different ores are mined along the life of the mine. This paper investigates a novel approach based on simulating the grades feeding the processing plant. In situ 3D grade models are built using geostatistical simulations. Grade spatial continuity and variability are reproduced in models that mimic the real deposit. These models are used in mine planning and scheduling transforming a 3D block model into an one dimensional string of values feeding the plant (one dimension flow). These grades have the statistical characteristics of the unknown real grades and can be sampled to emulate a variographic experiment. The results showed consistency and adequacy to estimate the sampling error (Gy, 1998 p 31) for various sampling intervals using the simulated grades. Also the results show a variographic experiment can change significantly from time to time, as ore changes and a selected sampling protocol can become obsolete if not adjusted for ore variability.CITATION:Costa, J F C L and Marques, D M, 2012. Defining a sampling strategy for a continuous flow supported by geostatistical simulations, in Proceedings Sampling 2012 , pp 3-8 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By D Craw, P Upton

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Otago Schist belt of southern New Zealand hosts widespread orogenic gold deposits. Erosion of these orogenic gold deposits has led to the formation of numerous placer deposits distributed across and beyond the host schist belt. Numerical modelling of crustal scale deformation and geomorphic evolution has defined the key tectonic features that have controlled the severance of detrital gold deposits from their sources. Tectonic activity over the past 20 million years, during development of the modern Pacific-Australian plate boundary, has severed links between some placers and their sources. Detrital gold was transported south from the Otago Schist source region in two different river systems in the Miocene. Mesozoic orogenic gold deposits shed gold into rivers that flowed to the south. These rivers were terminated by the rise of north-west-trending basement ridges at the boundary between weak schist crust and strong greywacke crust, and the ridges were controlled by pre-existing faults at that rheological boundary. In contrast, rising mountains close to the developing plate boundary in the Miocene were the locus of new orogenic gold deposits hosted in extensional faults. These gold deposits were rapidly exhumed and contributed detrital gold to orogen-parallel Miocene rivers that flowed to the south-west. Pleistocene deformation on mainly north-west and north-east orientations, and associated river capture, has severed the links between these Miocene orogenic deposits and downstream detrital gold.CITATION:Craw, D and Upton, P, 2015. Tectonic severance of links between placer gold and its sources, southern New Zealand , in Proceedings PACRIM 2015 Congress, pp 541–544 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By D Craw

Formation of gold-bearing veins in Otago Schist was intimately linked to the structural evolution of the schist belt. The currently-exploited Macraes gold deposit formed in a regional scale shear zone during latemetamorphic uplift of the schist belt. Further exploration for this type of deposit will be facilitated by an increased understanding of the late-metamorphic structural evolution of the schist belt. To this end, a three-dimensional cross section through the Otago Schist has been drawn using structural data gathered at outcrops in a 20 - 40 km wide transect across central Otago. This is the first continuous detailed structural section to be drawn through the belt. The section spans an area from Textural Zone 1 metagreywacke of the Torlesse terrane in the northeast through TZ 4 schist in the central region and across the Caples-Torlesse boundary to Textural Zone 3 schist of the Caples terrane in the southwest. Two different late-metamorphic structural generations are identified in this section: the long-recognised Manorburn Generation, and a new æPoolburn GenerationÆ. The location of the Caples-Torlesse boundary has been refined on this transect by field mapping combined with whole rock geochemistry.

Jan 1, 2001

Interest in mining narrow, vein-type ones has increased world-wide during the last few years despite the fact that prices of metals have not risen in proportion as production costs of mining, such as labour and energy. In many mines, where narrow ones are mined, the mining technique and equipment used have been poorly mechanised. The mining methods have been cut-and-fill or shrinkage stoping. Pneumatic jack-legs have been used for drilling and slushers have been used for loading. The methods that have been used can be called the 'first-generation' methods. Work has been very hard for miners. It has been dangerous and exhausting. Production volumes of mines, and a s a result of that, also profits have been low.

Jan 1, 1990

By T van der Meer, A Salokannel, M Martikainen, L M. Nevatalo, J McCulloch

Water use and wastewater management is becoming a focus for many industries around Australia and the rest of the world. Good quality water is increasingly being recognised as a precious resource, and regulations on the bulk storage and discharge of waste streams is becoming more stringent in order to protect the environment, existing water reserves and the communities that use these resources. Components such as heavy metals, arsenic, cyanide, and sulfate from acid mine drainage are some that occur at mining and metallurgical processing sites. Removal of such components can allow safe re-use of these streams, reducing the new water requirements of the process, or else allowing acceptable discharge to the environment. Re-use or discharge of treated water eliminates or reduces the risk associated with storage of large volumes of contaminated water on site.Technologies where a contaminant is selectively precipitated and removed as a sludge are used for many of these treatments. Selection of the best treatment option for wastewater must depend on what is suitable to each site, and consider not only the nature of the contaminant, but also other aspects, including the location and situation of the site, local regulations, cost of reagents, the sensitivity of the local environment and waste sludge disposal options. To outline how an effective and economical solution can be designed and delivered, this paper will present a case study for the removal of arsenic from a site wastewater, from assessment of the problem, selection of suitable technology, design and implementation, to the benefits delivered to the site.CITATION:Salokannel, A, Nevatalo, L M, Martikainen, M, van der Meer, T and McCulloch, J, 2013. Technology selection for removal of contaminants from an industrial wastewater, in Proceedings MetPlant 2013 , pp 531-538 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By W P. Darcey

Jabiru Metals completed a feasibility study on the Jaguar Base Metal Project in July 2005. The study was based on conventional truck haulage via a decline. Conveyor haulage was considered but not in sufficient detail to provide a meaningful comparison. The current study investigates the cost and productivity of alternative ore transport systems for the Jaguar project. The options considered are conventional underground truck, conveyor, road train, rigid frame truck, monorail haulage and shaft hoisting. Shaft hoisting was not considered in detail due to the high capital outlay for such a relatively short mine life of less than six years. This study goes beyond the common approach of evaluating haulage systems in isolation; it includes development costs, timing of ore production and costs associated with mine services as well as administration and milling costs. The results of this study indicate that the best haulage option for the Jaguar project is conventional truck using the Hitachi AH400 trucks. The net present value (NPV) for this option is A$8.13 million higher than the next best option namely the Kiruna E635 electric truck. The conveyor option has the lowest operating cost per tonne of ore but the longer development time negatively impacts on its NPV. The monorail option is considered impractical due to the number and length of trains required to achieve production targets.

Mar 21, 2011

The discovery since 1990 of four major orebodies in the Mt Isa Inlier - Century Zn-Pb, Osborne Cu-Au, Cannington Pb-Zn and Ernest Henry Cu-Au - only serves to enhance the already high stature of the Inlier in world mining importance. Currently the known mineral resources of the Inlier represent about 11 per cent of the world's Pb-Zn resources, five per cent of the world's Ag resources, and one per cent of the world's Cu resources. More can be expected to be added to these impressive figures given that two-thirds of the Inlier remains obscured by younger cover. Individually, projects such as Century and Cannington may ultimately achieve `world's best' status; Century's proposed production of 450 000 tpa of Zn metal would rank it close to number one with Cominco's expanded Red Dog project in Alaska. Cannington, with projected production of 660 tpa Ag, could become the world's biggest producer of silver. For comparison, Mt Isa produced 170 000 t of zinc metal and 335 t of silver in 1995. The apparent physical diversity of deposits in the Mt Isa Inlier is matched by a great diversity of opinion as to their origins. Because Ernest Henry is hosted by `porphyries', it is described by some as a porphyry copper deposit, despite mineralisation age possibly post-dating volcanic age by 200 Ma. Cannington Pb-Zn could be a Broken Hill-type (BHT) exhalitive deposit, or a late epigenetic replacement `regional skarn'. Mt Isa - Hilton Pb-Zn deposits appear to have experienced all deformational events and he syn-diagenetic in origin, or may have experienced little of the above and be epigenetic replacement deposits formed late in the major Isan orogeny, some 150 Ma after deposition.

Jan 1, 1996

How the Australasian and Canadian Codes (VALMIN and CIMVal) approach mineral property valuation is described. Brief comment is also made on the International Valuation Standards CommitteeÆs interest in a global valuation standard for Mineral (Extractive) Industries and the South African SAMREC initiatives to adopt a VALMIN-like Code. The conventional tripartite classification of valuation approaches into those that are Market-based, Income-based and Cost-based is outlined. It is best practice to use as many of these approaches as possible (and as many methods as reasonable in the particular circumstances), given the quantity and quality of the data available on the Mineral Asset (which depends upon the state of development of the mineral property). The use of specific methods must satisfy the basic considerations of logic and reasonableness and the purpose of the valuation. The competence, judgement and repute of the valuer are critical factors, since all valuations are time and circumstance specific. What constitutes æMarket ValueÆ in the different jurisdictions is discussed and definitions are given. Challenges facing the globalisation of a VALMIN-type Code for the international Minerals Industry are the influence of real estate valuers and the US jurisdictional idiosyncrasies. This is mainly due to a fixation on real property rights with a preference for using real estate-like comparative sales techniques (Market Approach) to the exclusion of Income-based approaches; a regulatory reluctance in the US to accept that Resources have considerable value; and the International Accounting Standards BoardÆs preference for Historical, rather than Current Value, accounting.

Jan 1, 2002

Green policies have gained momentum since the 1972 Stockholm, Environment Conference. The environmental movement has influenced political initiatives both in New Zealand and abroad. Governments and international institutions have addressed local, regional and global environmental issues with varying degrees of success. New Zealand so far has not supported the United Nations' call for sustainable development in a consistent manner. New institutions and new rules for resource management mean there are opportunities to look after the land in different and more ecologically sensitive ways than has happened in the past. The increasing influence of regional councils in resource management planning will have important implications for mining and mineral exploration. These trends are discussed and possible future events outlined. Green policies have gained momentum since the 1972 Stockholm Environment Conference. Environmental issues are now global and the twentieth year Environment Conference planned for 1992 is likely to see new commitments made by world leaders and their national governments. Green politics may be the popular trend of the moment but green principles of managing the earth's resources are here to stay. There are many businessmen, many technologists, and many politicians who have hoped that the environmental movement was a passing fad and would fade into oblivion. The evidence is otherwise. Far from passing into oblivion, the environmental movement is growing rapidly. Each year brings further scientific data that indicates mankind is on a self destructive course unless we learn how to better manage the earth's natural resources. This information has contributed to a growing population of environmentally aware people. In the last 20 years there have been messages of concern about a population increase out of control and the energy crisis which focused on dwindling oil stocks. The issues are all interrelated including the present global issues of climate change and thinning ozone layers. The attention being given the messages by the United Nations and member states requires similar attention by industry. The problems have been identified; the challenge is to determine what should be done about them. Every challenge brings new opportunities and the future need not be doom and destruction. Mining is seen by some of the environmental action groups as unnecessarily destructive of the environment, but I do not see mining ceasing in the next few decades. Rather, the rules will be clearer with some areas excluded from mining, the methods of extraction will improve, the technology of processing will become more sophisticated and restoration of mining sites will be not only normal practice worldwide, but the end result may leave no hazards, may enhance the landscape and may result in acceptance of the industry by the general public. For that to happen, commitment and cooperation is required between the industry, the government, and society. As an Officer of Parliament my role is to review the system of agencies and processes established by Government for allocating, using and preserving natural resources and to report whether the system is maintaining and improving the quality of the environment. I also have a responsibility to see that the environmental planning and management carried out by public authorities is effective. That Ineans I have a keen interest in how the mining industry is administered by New Zealand public authorities, including Ministers of the Crown and district and regional councils. Today I intend to review the approach to resource management being taken by international agencies and by the New Zealand Government, and to comment on how environmental impact assessment for mineral exploration, as well as mining, may be administered in the future.

Jan 1, 1990

By M Gwynne

McArthur River Mine is located approximately 50 km south-east of the NT township of Borroloola and approximately 120 km from the Gulf of Carpentaria. The mine hosts a series of layered shallow dipping tabular orebodies, with current reserves of approximately 22 Mt, grading 13.6 per cent zinc, 6.3 per cent lead and 65 g/t silver. Owing to economic considerations, the lower most orebody (No 2 orebody) has been selected for initial mine production. Following the completion of the No 2 orebody, mining will transfer to the lower grade and metallurgically more complex No 4 orebody. The mine employs a total of 235 people throughout the underground and surface areas. The majority of the workforce work a fly-in/fly-out, seven-day- on/seven- day- off roster with 12-hour shifts. Presently, a further 18 contractors are involved in trial mining areas. An apparent dip room and pillar technique has been selected as the primary mining method. Officially opened in September 1995, the current production rate of 1.2 Mt per annum will eventually escalate to 1.5 Mt per annum. Though most production is achieved through the use of conventional loaders, trucks and jumbos, the recent development of methods utilising scrapers, hand held machines and modified jumbos has produced encouraging results in steeper dipping areas of the mine. Initial production has been hindered by several factors including extensive and largely unpredictable faulting, worse than expected ground conditions and difficulties with some mining equipment. Compounded by the relatively thin 3 m ore seam, initial mining resulted in high dilution and poor production. This paper describes the development of unique planning and production systems that were evolved in order to overcome these problems and achieve the targeted production rates and head grade.

Jan 1, 1998

By T DePetris, B B. Beamish

There has been a gradual increase in the volume of internationally traded thermal and coking coal, with emphasis on blending of coals rather than single coal usage. New Zealand can take advantage of this situation, especially with its low ash and sulphur content coals. However, there is a need to clarify the thermal and coking behaviour of these coals as they relate to other market players, to benefit both the consumer and supplier. The high volatile matter contents of New Zealand coking coals are due to their high vitrinite content, which causes them to demonstrate stronger coking properties over a wider rank range than Gondwana coals. These same high vitrinite levels appear to correspond with lower initial softening temperatures than for Gondwana coals of similar rank. Preliminary results using thermogravimetric analysis also suggest that New Zealand high volatile bituminous coals can be used to substitute for higher rank Gondwana coals in combustion processes.

Jan 1, 1994